The effects of land-use history on soil properties and nutrient dynamics in northern hardwood forests of the Adirondack mountains. Ecosystems 7

Soil nutrient pools and nitrogen dynamics in old-growth forests were compared with selectively logged stands and stands that were selectively logged and then burned approximately 100 years ago to test the hypothesis that land-use history exerts persistent controls on nutrient capital and nitrogen (N) transformation rates. We provide esti-mates of net N mineralization and nitrification rates for old-growth forests from the northeastern United States, a region in which few old-growth forests remain and for which few published accounts of mineralization rates exist. At the plot level, no ef-fects of the dominant tree species were observed on any measured soil properties or N-cycling rates. Effects of alternate disturbance histories were de-tected in soil carbon (C) and N pools. Old-growth forest soils had higher total C (67 Mgha1) and N capital (3.3 Mgha1) than that of historically logged then burned soils (C 50 Mgha1 and N Mgha1), with intermediate values (C 54 Mgha1 and N 2.7 Mgha1) in the stands that were historically logged. Despite these differences in C and N content, corresponding differences in C–N ratio, net N mineralization rates, and net nitri-fication rates were not observed. The N concentra-tion in the green foliage of American beech trees (Fagus grandifolia) was also highest from canopy trees growing in old-growth stands (3.0%), fol-lowed by logged stands (2.6%), and lowest in the logged/burned stands (2.2%). These data suggest that some legacies of light harvesting on ecosystem processes may be detected nearly 100 years follow-ing the disturbance event. These results are dis-cussed in the context of how multiple forest distur-bances act in concert to affect forest dynamics. Key words: Adirondack Park; disturbance; fire; logging; nitrogen cycling; old growth; temperate forest